Rifle broaching machine



y B. WELTE E T AL ,87

RIFLE BROACHING MACHINE I Filed Jan. 24', 1942 3 Sheets-Sheet T I M W W fiazredz'ci Harry /7 J 6 y I v r TTORNEYS.

" July 4, 1944.

B. WELTE m1.

RIFLE BROACHING MACHINE .3 Sheets-Sheet 2 Filed Jan. 24, 1942 July4, 1944. ELTE A 2,352,873

RIFLE BROACHING MACHINE I 3 Sheets-Sheet 3 Filed Jan. 24, 1942 [1v VE TOR$ ,Beyeaicz 1442/ a,

TORNE Y5.

Patented July 4, 1944 RIFLE BROACHING MACHINE Benedict Welte, Lake Orion, and Harry H. Gotberg, Detroit, Mich, assignors to Colonial Broach Company, Detroit, Mich-.-, a corporation of Delaware Application January 24, 1942 Serial No.-428,044

4; Claims.

The presentinvention relates to a machine for broaching the interior of relatively long tubular members, and is particularly adapted for use in rifling gun barrels.

It has been suggested that in broaching gun barrels and the like the cutting portion of the broach be immersed in oil under pressure, which oil or other suitable coolant is forced through the gun barrel in the direction of the movement of the broach during the broaching operation.

The machines hitherto devised'for accomplish-- ing this object have not been well suited to mass production methods in view of the fact that they have required a-close, non-leaking fit between one end of the gun barrel and a fixture through which the broach passes and to which the coolant under pressure is supplied.

Accordingly, it is one of the principal objects of the present invention to provide a machine for broaching the interior of relatively long tubes, such as is required in the rifle broaching of'gun barrels, in which it is unnecessary for the operator to-make a leaf-proof connection between the gun barrel and the fixture which supplies the coolant under pressure.

A further object of the invention is to provide a machine of the type described in which the breaching operations may becarried on'with a minimum of efiort on the part of the operator.

Other objects and advantages of the invention will become apparent from the following specification, the drawingsrelating thereto, and from the claims hereinafter set forth.

' Referring to the drawings, in which like numerals are used to designate like parts in the several views throughout:

Figure 1 is a fragmentary, side elevational view of the completemachine, withparts broken away to show the interior construction;

Figure 2 is a fragmentary plan view of the machine;

Figure 3 is a fragmentary, transverse section taken on the line 3-3 of Figure 1;

Figure 4 is an enlarged, longitudinal section of that portion of the machine indicated by the letter A in Figure 1; g

- Figure 5 is a fragmentary, longitudinal section of that. portion of the machine indicated by the letter B in Figure 1;

- Figure 6 is a fragmentary, longitudinal section of thatportion of the machine indicated by the letterC in Figure. 1;

Figure 7 is a transverse sectionitaken on: the line T -F'I oLFigure 5;

a. Figure 8 isa transverse section taken on the line 8-8 ofFigure 6:. and V s Figure 915 a view showing a formjofj gun barreladapted toberriiiedin' the machine. .7 l 7 Referring particularlygto Figures 1 and. 2,, it will be seen that the machine comprises a main basecasting 10 of general boxslike form provided with a 'pair of'longitudinallyextending rails H upon "which is mounted a longitudinally movable cylinder slide I2. I

' As best shown in'Figurefl; the cylinder in slide I2is provided with a piston. l3, which is. connected by means :of a double walled'piston rod to amanifold l5'by means of which fluid under pressure can be l'supplied to either side of .the piston to effect movement" of the cylinder slide. The construction and arrangement of the means for supplying fluid to the cylinder may be of any desired orconventiona'l' form, and need not be further' described. '1 f I a A pair of longitudinally extending guide bar's H are mounted upon-the rails II, and overlie a laterally projecting longitudinally extending rib I8 formed 'ori'th'e cylinder slide l2 to hold the slide in position on the rails "l l.

A pull head 20 *iss'ecured to the upper surface of the cylinder slide I2 in any suitable manner, and carries a'rotatablespindle' 2i toiwhichthe shank 22 of a broach pulling chuck 23 is secured. A spiral lead bar "M'is'keyed'to the spindle l2 by means'of a key 25;'and projectsrearwardly from the'pull head 'ZU'jthr'ough an upstanding bo'ss'26 fixed to the base of themachine'at oneend of the latter. The boss 26. contains a lead'nut 21 provided with internal spiral ribs- 28'which fit within the spiralt:grooves 29 of the lead bar 24 to cause rotation of thela'tt er as thelead bar is moved longitudinally with the pull head 28 and thercylinderslid'e l2. On' th'e rear face of'the boss is mounted a" tubular'jhousing 30, which is of sufficient lengthitoentir'ely' enclose the lead bar when it is inits 'extreme:limit of projection at the. rear of'ithem'achiner The'machine is providediwithta; work'ho'lding fixture indicated generally: at 34, which fixture comprisesapair jof longitudinally extending base portions: 35? connected" by a transverse portion 36 having an upstandingtransversel wall 31. The longitudinal base'portions are adjustably secured to'Ithe upper; surfaces of:guideg'bars' Is! by any suitable. means, such; as bolts? 38'; The transverse portion "36 of the workfixture casting is provided witha central. longitudinally. extendingboss 39, provided with a central boreMl adapted to -receive' a removable sleeve 4! which is approximately of the same internal diameter as the external diameter of the large end of the gun barrel or other workpiece.

The sleeve 4| is preferably so dimensioned that it will receive the workpiece with a slip-fit, so that it will hold the workpiece in proper alignment and yet will permit insertion of the workpiece by hand. I I The sleeve 4| is held in position in the bore by a ring 42 secured by cap screws :33 to the end of the boss 39 and overlying a flange 44 on the end of the sleeve. The sleeve 4| is shorter than the bore 40, and in the-right-hand.

end of the bore is fitted a thrust sustaining ring 45 which is held in position by a cover plate 46 secured to the boss by cap screws "4l|. The ring 45 is of smaller internal diameter than the sleeve 4|, so that the workpiece will abut against the ring when it is positioned within the sleeve;

broach from injury, The opening in the liner-v 50 is slightly larger than the maximum diameter ofthebroachn As best shown in- Figure '7, the work holding fixture 35 is provided with .a means to. clamp the work in broaching position. The clamping means is mounted within a transverse bore 52 3 extending through theboss 39 at right angles to the bore 40 but displaced from the axis of the bore 49. drical clamping element 53 having an upwardly extending stem 54 uponv which is threaded a, handle 55. A sleeve 56surrounds the stem 54 between the handle and the clamping .element 53. The cylindrical element 5.3 and the cylindrical sleeve 56, which are of the same diameter, are of sufficient size to intersectthe bore of, sleeve 4|, but they are cut away, as indicated at 51, in order to conform to the cylindrical contour of the bore in sleeve 4|.

Means are provided for preventing rotation of the element 53 and the sleeve 55, which means comprises a pair of set screws 58 and 59. having terminal portions extendingrinto longitudinally extending grooves 60 and 6! in the element 53- and sleeve 56, respectively. .It will. be apparent that as a result of this arrangementturningoi the handle in a clockwise direction, as viewed in; Figure 2, will force the clamping element 53 and the sleeve 56 toward each other and cause them to clamp the workpiece .positioned withinthe. bore of sleeve 4|.

As best shown in Figure 5, at each side of the stem 54 the sleeve 56 is provided with a bore 64 adapted to receive a plunger 65, which is forced downwardly by a spring 66.. The plungerand springs, which are duplicated at opposite sides of the stem 54, separate the clamping element 53 and sleeve 54 when the handle 55 is rotated counterclockwise, andthus insure release of the workpiece. The fit ofthe cylindrical clamping element 53 and sleeve 56 in the transverse bore 52 is substantially accurate to prevent any ap-.-

preciable leakage of fluid under pressure from;

-Welding. The tubular housing .68. is of sufi'cient internal diameterto receive theworkpieceeand Mounted within the bore 52- is a cylin-.

provide, at least adjacent the outer end of the" tubular housing, a space within the housing and surrounding the workpiece, for a reason hereinafter indicated.

The housing 68 may be of any desired length, but is preferably so proportioned that when the workpiece 69 is fitted within the sleeve 4| and seated against the ring 45 it projectsv outwardly beyond the end of the tubular housing 68, so that it may be readily grasped and removed by the workman.

The tubular housing 68 is provided at its free extremity with a tubular extension 10, which is removably secured to the end of the housing by means forming a bayonet joint. As best shown of housing 68 and surrounded by a rotatable ring 12. Ring 12 is provided with a pair of pins 13 which extend inwardly into a pair of slots 14 in the ring. 1|. Pins 13 and slots .14 permit a limited rotation of the sleeve 12 relative to the housing.

The ring vl2 is provided with an enlarged end portion I5 having a counterbore into which may. be. fitted an enlarged portion 16 on a ring .11; which-is welded at 18 to the tubular extension E0. The enlarged portion 15 of the ring 12 is, provided with .conventional bayonet slots. I9, adapted .to interlock with pins 80 projecting out; wardly from the enlarged portion 18 of ringfll. The enlarged portion 16 of .thering 'l'l is provided with a counterbore in which is mounted an oil seal 82 of any desired or conventional construction., As a result of this construction,- the tubular extension |0 may be readilyremoyed or attached to the end of the tubular housing 58. by simply rotating the sleeve 12 to release the bayonet slot connection," and the seal 82 prevents leakage of liquid under pressure from thein terior of the housingvand tubular extension.

The outer end of the tubular extension;'| is closed in any suitable manner, as by a closure; plate 83, and thecombined housing formed by the tubular housing 68 andextension 10 is ofsufficient'length to completely enclose the entire:

workpiece and also the cutting p'ortion 8j4 o f a breaching tool when the noncutting shank por-, tion 85 of the broaching toolis projected entirely through 'the'workpiece and into the pullingrcliuck' 23 of the machine. The't'ubular housing 68 is provided with a fluid; line 8'! which leads from any suitable sourc"(not shown) of'oilorother coolant'under pressure to the interior of thehousing GB. "I'he'mezms for supplying oil or other coolant'to the interior ventional construction, but'preferably includes a pump which is automatically started wherr the operator initiates the 'broach pulling movement" of the cylinderslide' '|'2.- "The hydraulic'cim it valves and controls for actuating the cylinder slide I2, being of conventional construction; are not shown or described. I r 1 The machine ofthe present invention-is' oper ated in the following manner y :zs

The'tubular extension-1|) is rerno'ved by ma nipulating its bayonet and slokconneetion with the tubular housing 68. and the-workpiece-i's-inserted to the position shown'in Figure 4 which' its inner end abuts against the thrustring 45:- The workpieceis then clampedcinzthat position by -manipulation of the handlo55'y. 'Ihereupom the broaching tool is insertedthroughlthe worke piece .irom its; outerv end, until ;the entire noncutting shank portion of;the.broach;extend8..

through the workpiece andinto'the pulling chuck- 23. This leaves the cutting :portion .84 of the broachingtool projecting from the outer end of the workpiece, as best indicated at Figure 4. The tubular extension H1 is thenfitted over the projecting end of the broach and workpiece and secured to the tubular housing by the aforemene tioned bayonet and slot connection. Thereupon fluid under pressure isadmitted to the tubular housing 68, and the machine is started to efiect the broach pulling movement of the slide [2. I

It will be observed that, inasmuch as the outer end of the tubular housing 68 as well as the tubular extension 1E] are of larger internal diameter than the external diameter of the workpiece, the fluid coolant under pressure will flow from pipe 81 into the space surrounding the workpiece and broach and will completely immerse the broach in the fluid. In addition, the coolant, which is preferably under a relativelyvhigh pressure, will flow through the workpiece in a space surrounding the broaching tool. This flow of coolant under pressure through the broaching tool continues throughout the broach cutting stroke, and it will be observed that the flow is in the direction of the cutting stroke and hence will=assist in the removal of chips.- Since the space between the broach teeth and between the shank of the broach and the interior "of the workpiece is exceedingly small, particularly in rifle broaching'operations, andthe fluid in housing 68 and tubular extension is underhigh-pressure, the rate of flow of fluid through the workpiece during the broaching operation is exceedingly high. This not only materially assists in chip removal, but facilitates cooling of the work and broach teeth during the long cutting stroke which the teeth must make in passing through the workpiece.

It will be noted that during the broach pulling operation the spiral lead bar will effect a controlled rotation of the pull chuck and, consequently, the broach end thus will cause the broach teeth to follow the spiral path necessary to effect a rifling operation. It is obvious that where a non-spiral broaching operation is desired, the lead bar may be omitted. Moreover,

. under certain circumstances it may be possible to omit the spiral lead bar even when forming rifle grooves, provided the broach is constructed to follow its own spiral path and the pull chuck 23 is freely rotatable.

On completion of the broach pulling operation, the machine and the pump which supplies coolant under pressure to line 81 are both stopped, and the tubular extension 10 is removed from the end of housing 68. This tubular extension will at that time contain a substantial body of residual coolant, which may be permitted to flow onto a sheet metal pan 90 which underlies the tubular housing 68 and a major portion of the xtension 18. Suitable means are provided for returning the coolant which falls in pan 99 to the tank or other source of coolant connected to the coolant pump.

If the broaching operation is to be carried out by the operation of two or more separate broaches in succession, the operator, on removal of the tubular extension Til, inserts a new broach into the workpiece and into the pull chuck 23 which, of course, must have been freed of the first broach and brought back to its starting position. The cycle of operations is then repeated, as above described. When the broaching operation on a workpiece is completed, whether by the operation of one or.:more broaching tools, the operator removes the tubular extension Ill and withdraws the workpiece 69 from the sleeve 4| and housing 68, replacing it by a new'workpiece. Thereupon, the cycle of operations is repeated.

It will be apparent that there is provided in accordance with the present invention a machine in whichv the difiiculty of making a fluid-tight connection between the interior of the workpiece and a source ,of fluid under pressure-is entirely eliminated by positioning the workpiece. within a housing filled with fluid under pressure. Since the only outlet to that housing is through .the opening in the thrust, sustaining ring 45, against which the work abuts with a heavy pressure during. the broaching operation, no appreciable leakage around the exterior of the workpiece and out of this opening is possible. Accordingly; the workmanmaysimply freely insert the workpiece in position and then close the housing by attach-' ing the removable extension 10. Moreover, since the sleeve 4i holds the workpiece in accurate alignment, it is unnecessary to provide a detachable support for the opposite ends of the workpiece. Whileonly one form of the invention is illustrated and described herein, it is apparent that variations in the details and designof construction may be indulged in .without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is: a t 1. In a pull broach machine for broaching the interior of a relatively long tubular workpiece, a member having a socket adapted to receive and fit one end of said tubular workpiece and support the workpiece in broaching position, an axial thrust sustaining shoulder associated with said socket and adapted to engage a portion of said workpiece and sustain the thrust induced by a broaching operation, the bottom of said socket having an opening to permit passage of a broaching tool therethrough, a tubular housing fixed at one end to said member and enclosing the opposite promoting end of said workpiece, said housing being of suflicient length to also enclose the projecting cutting portion of a broaching tool when the non-cutting shank portion of the tool is projected through the workpiece from said opposite end thereof and through said opening in the bottom of said socket, said tubular housing having a demountable free end portion to permit insertion and removal of the workpiece and insertion of the broaching tool, means to grasp the shank of the broaching tool when it projects through said opening in the bottom of the socket and to pull the broaching tool through the work, and means to supply coolant under pressure to said housing to cause a flow of coolant through the workpiece in the direction of movement of the broaching tool.

2. In a pull broach machine for broaching the interior of a relatively long tubular workpiece, a. member adapted to abut against one end of the workpiece and sustain the axial thrust induced by the broaching operation, said member having an opening for passage of a broaching tool therethrough, a tubular housing extending from said member toward the opposite end of the workpiece and entirely surrounding said workpiece, said housing being closed at its end and of sumcient length to also enclose the projecting cut ting portion of a broaching tool where the noncutting shank portion of the tool extends through the workpiece and said member, means within said" housing for clamping andholding the workpiece. in position within the housing andnin abutment with said member, a control elementforoperating said clamping means extending through the wall .of said housing, said housing having a demountable endrportion to permit insertion and. removal of theworkpiece and insertion of the broaching tool, means to grasp the shank of the breaching toolwhenit projects through said opening in thebottomiof the socket and to pull the breaching. tool through theflwork, and means tov supply coolant under pressure to said housing tocausea flow :of coolant through the workpiece in the'direction'of movement of the broaching tool. e A

3. In a pull broach machine for broachingthe interiorof a relatively long tubular workpiece, a memberadapted to abut against one end of the workpiece and sustain the axialrthrust induced by the broaching operation, saidmember having an opening for passage of a breaching tool there'- through, a tubular housing extending from said member toward the opposite end of the workpiece and entirely surrounding. said workpiece, said housing being closed at its end and of sufficient length to also enclose the projecting cutting portion of a broaching tool when the non-cutting shank portion of the tool extends through the workpiece and said member, means within. said housing for clamping and holding the workpiece in position within the housing and in abutment with said member, a control element for operating said clamping means extendingthrough the wall of said. housing, saidhousing having a demountable end portion separable iromthe remainder ofthe 'housi'ng at a point along th'e length thereof intermediate the ends-of the work piece-to permit insertion. and removal of the workpiece and insertionrof the broachingvtool, means to grasp the shank of .the broaching tool whenitprojects through said opening in the bottom of the socket and to pull the broaching tool through the work, and means to supply coolant under pressure to said housing tocause a flowlof coolant through the workpiece in the directionof .movementof the broaching tool.

4- In a pull \broach machine for broaching the interior of a relatively long tubular workpiece, a work fixture including a tubular housing adapt-. ed toenclose the workpiece andthe cutting por-.- tion.of thebroach and having a thrust sustains ing abutment atone end, vvmeans to supply cool? ant under pressure to. said housing, a sleeve mounted in said housing adjacent said. abut ment and adapted to fit one end of theworkpiece and hold the entire workpiece in alignment with the, path of travel of the broach, the opposite end of the work being freely. suspended in .said housing,,means operable from the exterior of said housing for clamping the workpiece in .said sleeve, said last named means comprising a pair of cylindrical elements movable toward each otherin a transverse bore formed in the walls of said housing and intersectingthe bore of said sleeve in offset relation, andsmeans for forcing said cylindrical elements toward each other and into engagement with the workpiece.

HARRY H. GOTBERGI, BENEDICT WEL'IE. 

